Insulin is often
described as being either 'natural' ('animal') or 'human'. The sequence
of amino acids (building blocks that make up the protein) is slightly
different in insulins from different species. The insulin that humans
make differs from that which pigs and cows make. Porcine insulin has one
different amino acid and bovine insulin has three different amino acids.

Insulin is produced
by beta cells in the pancreas and is the most important hormone in the
body to regulate blood glucose levels. A partial or complete lack of
insulin causes diabetes, which, untreated, is often fatal by the teenage
years. Before insulin was discovered, diabetes was managed through diet,
which allowed patients to survive, but generally for just a few years
after diagnosis.

Manufacturing Process

Synthesizing
human insulin is a multi-step biochemical process that depends on
basic recombinant DNA techniques and an understanding of the insulin
gene. Manufacturers manipulate the biological precursor to insulin
so that it grows inside simple bacteria. While manufacturers each
have their own variations, there are two basic methods to
manufacture human insulin.

A leading
manufacturer of life-saving products like heparin, gonadotrophins
and insulin, produced from animal tissues using biochemistry pays
special attention to the source of the materials to avoid
contamination with pathogenic microorganisms or toxic substances.
Their manufacturing processes have undergone virus validations -
studies in which virus removal is proven - just in case a virus is
present despite all precautions.

Applications & Technology

The dose of
insulin used to obtain diabetic control was reduced by 7% in 108
patients treated solely with very pure porcine insulin from the
start of insulin treatment when compared with 108 matched patients
who had received conventional insulins. In 117 patients whose
treatment had been changed from conventional bovine or
bovine-porcine insulin to very pure porcine insulin the dose was
reduced by 9%.

Insulin is
synthesized as a larger precursor, preproinsulin , which is rapidly
cleaved to proinsulin. The conversion of proinsulin to insulin is
then a relatively slow process, which is thought to commence in the
Golgi apparatus and continue into the maturing secretory granule.

These factors led
researchers to consider synthesising
Humulin by inserting the insulin gene into a suitable vector,
the E. coli bacterial cell, to produce an insulin that is chemically
identical to its naturally produced counterpart. This has been
achieved using Recombinant DNA technology. This method is a
more reliable and sustainable method than extracting and purifying
the abattoir by-product

Market

Canada led the
world of biotechnology in 1921 when Banting and Best extracted a
biologically active hormone from the pancreas of dogs. This Nobel
Prize-winning work led to the isolation of insulin, which has been
used for the treatment of Type 1 diabetes mellitus ever since. It is
estimated that the present world capacity for cell culture
production stands at 475,000 litres, 75 per cent of which is
controlled by biopharmaceutical companies and the remainder by
contract manufacturers.

Over 150
biopharmaceuticals have now been approved for human therapeutic use.
This drives the annual global market for biopharmaceuticals to over
$30 billion US 1,2. However, this success rate would not have been
possible without the incorporation of animal cell cultures into the
armoury of technologies for biomanufacture.